Recently, the most common calibration apparatuses and methods for non-crystal oscillators include two categories: 1. apparatuses and methods using the interval between SOFs (start of frames) of 1 ms±0.05% as the basis of calibration, and 2. apparatuses and methods using the width of synchronization sequence (SYNC) as the basis of calibration. The calibration accuracies of these two categories are influenced by the number of SOFs before the “setup token” command sent by a host.
Thus, how to further decrease the calibration time of the non-crystal oscillator to save the related manpower and material is worthy of further research and improvement.
Keeping the drawbacks of the prior art in mind, and persistently employing experiments and research, the applicant has finally conceived of an apparatus for automatically calibrating a clock of a non-crystal oscillator and a method thereof. The present invention forces the host to send the “in token” command continuously before the calibration reaches the required accuracy, and accurate data are sent to the host until the calibration has been accomplished to achieve the effect of self-controlled optimization.